Ionic interhalogen oxidizing agent and method

ABSTRACT

ClF6PtF6 is prepared by reacting PtF6 with ClF5 in the presence of ultraviolet light. ClF4PtF6 is also produced by the reaction and may be removed from the mixture by decomposition. ClF6PtF6 is useful as an oxidizing agent and as an intermediate in the preparation of other oxidizing agents containing chlorine in its +7 valence state.

Minted States Patent 1 [111 3,709,748 Roberto 1 Jan.9, 1973 [54] IONIC INTERHALOGEN OXIDIZING [56] References Cited AGENT AND METHOD UNITED STATES PATENTS [75] Inventor: Francisco Q. Roberto, Lancaster, 3 423175 1/1969 Horvitzetal 23/367X Calif i l [73] Assignee: The United States of America as jgzfz gfx g g iz53 3:1232 h represented by the Secretary of the Air Force Filed: May 26, 1970 Appl. No.: 48,614

ILLS. Cl. ..l49/109, 23/367, 204/157.l,

Int. Cl. ..C06h 15/00 Field of Search ..149/l09; 204/157.1; 23/367; 252/186 Attorney-Harry A. Herbert, Jr. and Cedric H. Kuhn [57] ABSTRACT ClF PtF is prepared by reacting PtF with ClF in the presence of ultraviolet light. ClFJtF is also produced by the reaction and may be removed from the mixture by decomposition. ClF PtF is useful as an oxidizing agent and as an intermediate in the preparation of other oxidizing agents containing chlorine in its +7 valence state.

6 Claims, No Drawings IONIC llNTERI-IALOGEN OXIDIZING AGENT AND METHOD BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the preparation of ionic interhalogen compounds.

2. Description of the Prior Art.

The use of interhalogen compounds such as ClF and ClF: and derivatives thereof such as CIR, as oxidizers for rocket propellants is well known by those working in the field. The success obtained with interhalogen compounds and their derivatives has led to increased interest in the development of methods and techniques whereby other potentially more active interhalogen compounds and interhalogen derivatives may be prepared. For example, interest in the field of interhalogen type compounds led to the preparation of ClF PtF from the reaction of CIF with HP}. The results of that preparation were reported by Roberto and Mamantov in lnorganica Chimica Acta, 2,

.317( 1968). The reaction was carried out in a nickel reactor and was found to proceed according to the equation: ClF PtF CllflPtF PEP}. However, research leading to the Inorganica Chimica Acta article revealed that the compound, ClFJtF decomposes slowly at room temperature under vacuum. Because of this tendency, the compound, although it is a strong oxidizing agent, is generally unsuitable as an oxidizer for solid rocket propellants.

SUMMARY OF THE INVENTION It has now been found that a new compound, CIF PtF may be prepared by reacting CIF with PtF in the presence of ultraviolet light. The reaction is preferably carried out in a sapphire reactor in order that it may be catalyzed by ultraviolet light and produces, along with ClF PtF ClF PtF as an impurity. The impurity, however, decomposes under vacuum at room temperature and effective removes itself from the product. Decomposition of the impurity may be accelerated by heating the'product to a temperature of approximately 85C for a short period of time. 7

DESCRIPTION OF THE PREFERRED EMBODIMENT invention is described below.

EXAMPLE Reaction of PtF and ClF Platinum hexafluoride (l.2 6 mmoles, 0.390 gram) and chlorine pentafluoride (3.78 mmoles, 0.49l gram) were condensed. Condensation was accomplished by allowing the gaseous reactants to flow into an evacuated 7-cc sapphire reactor which was precooled to -l96C by a liquid nitrogen trap. A sapphire reactor was utilized in order to permit catalyzation of the reaction by ultraviolet light. After condensation, the reactor and its contents were slowly warmed to ambient temperature and left exposed to ultraviolet light at 2223C for a period of about 8 days. It was observed that (1) red PtF gas disappeared and (2) the solid phase lightened from red-brown to bright yellow during the reaction. After about 8 days, the red PtF gas had completely disappeared and the solid phase was bright yellow. At that time the reaction was considered complete and excess unreacted ClF, gas was removed under vacuum and the solid yellow reaction product was weighed. The reaction product weighed 0.489 gram.

Equipment utilized in the above reaction included, in addition to the 7-cc sapphire reactor, a vacuum system constructed from inch nickel pipe and nickel lines at tached to the vacuum system for admission of reactants and passivating gas (F The lines were attached to the vacuum system by silver welding and monel valves were utilized to open and close them. The sapphire reactor was attached to a monel valve which, in turn, was attached to the vacuum system by means of a Swagelok fitting. A liquid nitrogen trap was utilized to cool the reactor to l96C. However, any refrigerant capable of lowering the temperature to 78C (dry ice temperature) or below could have been used. Also, the 8 day reaction time described above may be varied for a period of from 5 to 14 days.

Prior to the above-described reaction, the entire system was passivated with fluorine at 300C utilizing a heat gun.

After obtaining the bright yellow reaction product from the reaction described above, the product was analyzed according to the procedure described below.

Analysis of the Product Obtained from Reaction of PtF and CIF Analysis of products obtained from reactions similar to that described above showed that, under the conditions given, a mixture of about 50 weight percent ClF PtF and about 50 weight percent ClF PtF was obtained. When stored at room temperature, the ClF.,PtF removes itself from the product by decomposition leaving PtF, as a harmless solid impurity. The removal of ClF PtF may be hastened by heating the product.

To perform the analysis, the yellow solid was transferred, under nitrogen, to a 50 ml quartz reactor equipped so that it could be connected to the vacuum system. Prior to transfer of the product, the quartz reactor was purged with dry nitrogen and weighed in a dry box. After transfer, nitrogen in the reactor plus the bright yellow solid reaction product was weighed. Following weighing, the temperature of the reactor (and the product contained therein) was lowered to l 96C by placing the reactor in a liquid nitrogen trap. Then 5 to 10 ml (the amount varied in several runs) of doubledistilled water was transferred to the reactor via the vacuum system and lines attached thereto in order to hydrolyze the reaction product. The reactor (and product therein) was then warmed to ambient temperature, by removing the liquid nitrogen trap, and allowed to remain at ambient temperature for about one-half hour. Then the solution was refrozen by lowering the temperature as before to l96C, and 5 to 10 ml of hydrazine was added to the reactor in order to reduce platinum ions to platinum metal. (Like water, the amount of hydrazine added was different in different runs.) After addition of hydrazine, the reactor (and frozen mixture therein) was again warmed to ambient temperature. Solid platinum compounds formed by hydrolysis and platinum metal formed by reduction were filtered off and redissolved with aqua regia to yield chloroplatinic acid. The chloroplatinic acid was Analysis for ClF PtF Pt F Cl Calculated: Found:

X-ray diffraction patterns, infrared spectra, and Raman spectra were also obtained. Infrared and Raman Spectra The infrared spectrum of the reaction product obtained consisted of bands at 890, 875, and 540 cm which were assigned to ClF and a peak at 649 cmattributed to PtF Other bands indicated that ClF ions were also present in the reaction product. The 890, 875, and 540 cm bands were absent in the Raman spectrum. This absence indicates that the molecule is octahedral. Also, a comparison of the IR spectrum was made with that of the octahedral molecule SF Since ClF is isoelectronic with SP similarity in the spectra of the two compounds was expected and was found. The higher mass of the central atom in ClF was expected to cause a shift toward lower frequencies and this was observed for the infrared active bands. Bands for SP are at 940, 890, and 615 cm". Thus, the shift toward lower frequencies due to ClF was 50 cm(940 to 890), 15 cm(890 to 875 and 65 em"(6l5 to 540), respectively. X-Ray Diffraction The X-ray diffraction pattern for CIF PtF powder was relatively simple, indicating high symmetry. High symmetry is to be expected if both CIF and PtF; are octahedral. The X-ray diffraction data appear in the following table. Lines due to the presence of CIR, are not included in the table.

TABLE X-RAY DATA FOR ClF PtF d(obsd) d(calcd) hkl Intensity 5.7l7 4.036 3.328 2.576 2.334 1.999 L923 1.774 L727 1.530

2.569 2.345 2.030 l .915 L772 L732 1.535

Strong Very Strong Medium Light Medium Light Very light Very light Very light Very Light Further Characterization of the Reaction Product In order to further characterize the reaction product obtained from the above example, the yellow solid was reacted with excess ClF O and the materials produced by the reaction analyzed. ClF O was condensed by introducing it on top of the yellow solid at l96C and the mixture gradually warmed. At temperatures between C and 35C, CllZPtF present in the yellow solid reacted with CIF O according to the equation:

Above 35C, the melting point of ClF O, ClF PtF reacted with the ClF O according to the equation:

Upon formation, the ClF underwent further reaction according to the equation:

Thus, based on the weight of F C1F and ClF OPtF produced, the yellow reaction product from the example was calculated to contain approximately a 50:50 weight percentage mixture of ClF.,l='tF and CIF PtF The absence of F among the reaction products at temperatures below 35C indicated that ClF PtF was a reactant along with CIR-,0 at those temperatures. On the other hand, the appearance of F among the reaction products at temperatures above 35 C indicated that CIF PtF was a reactant along with CIF,,O at those temperatures. Removal of ClF PtF from the Reaction Product ClF PtF is known to slowly decompose under vacuum at room temperature. The decomposition proceeds according to the equation:

ClF PtF (solid) ClF (gas)+ PIE-,(solid).

The solid PtF undergoes further decomposition according to the equation:

Thus, if it is desired, CIFJtF may be removed from the reaction product merely by allowing the reaction product to stand in a dry box under vacuum until the ClF PtF decomposes. The decomposition leaves a minor amount of solid F'tF. (about 19 weight percent) as an impurity with the desired ClF PtF However, this impurity causes no adverse effects when CIF PtF. is reacted to product other oxidizing agents as described below. If it is desired, the decomposition of ClF PtF may be accelerated by warming the mixture. Warming to about C greatly speeds the decomposition process and even higher temperatures (up to 350C) may be used with no adverse effects on the ClF PtF Decomposition is considered complete when red PtF gas) is no longer produced. Uses of ClF PtF,

ClF PtF containing PtF as an impurity, may be utilized to produce other oxidizing agents by reacting it with certain suitable materials. Examples of some reactions are:

and

wherein M is an alkali metal such as Na or K and X is an element such as B, Sb, or As.

To carry out the reactions, CIF PtF and the second reactant are condensed together at -l 96C and then allowed to warm. When the melting point of the second reactant is reached the reaction begins and continues until the reactants are exhausted.

in reaction (1) above, the reaction products, ClF-, and ClF OPtF can be separated by taking advantage of the fact that ClF is a liquid at room temperature and ClF OPtF is a solid. in reactions (2) and (3) all reaction products are solids at room temperature and separation is accomplished by taking advantage of the fact that certain interhalogen solvents such as [F and BrF will dissolve the CIF XFI, and CIF XF compounds but not the MPtF compounds.

I claim:

1. A composition of matter having the formula ClF PtF 2. The composition of claim 1 which contains a minor amount of PtF as an impurity.

3. A composition which consists essentially of approximately equal parts by weight of ClF PtF and ClF PtF 4. A method of preparing a mixture of ClF PtF and ClF PtF which comprises:

a. condensing CIF and PtF by introducing same into a reaction zone maintained at a temperature in the range of about -78C to 196C;

b. warming said reaction zone to approximately room temperature; and

c. exposing said reaction zone and its contents to ultraviolet light.

5. The method according to claim 4 wherein said reaction zone is a sapphire reactor.

6. The method of preparing an oxidizing agent which contains Cl in its +7 valence state which comprises:

a. condensing into a reactor a first reactant consisting essentially of CIF PtF containing PtF as an impurity and a second reactant selected from the group consisting of ClF O, MXF and MXF wherein M is selected from the group consisting of Na and K and wherein X is selected from the group consisting of B, Sb, and As; and

. warming the reactants to the melting point of the second reactant. 

2. The composition of claim 1 which contains a minor amount of PtF4 as an impurity.
 3. A composition which consists essentially of aPproximately equal parts by weight of ClF6PtF6 and ClF4PtF6.
 4. A method of preparing a mixture of ClF4PtF6 and ClF6PtF6 which comprises: a. condensing ClF5 and PtF6 by introducing same into a reaction zone maintained at a temperature in the range of about -78* C to -196* C; b. warming said reaction zone to approximately room temperature; and c. exposing said reaction zone and its contents to ultraviolet light.
 5. The method according to claim 4 wherein said reaction zone is a sapphire reactor.
 6. The method of preparing an oxidizing agent which contains Cl in its +7 valence state which comprises: a. condensing into a reactor a first reactant consisting essentially of ClF6PtF6 containing PtF4 as an impurity and a second reactant selected from the group consisting of ClF3O, MXF4, and MXF6 wherein M is selected from the group consisting of Na and K and wherein X is selected from the group consisting of B, Sb, and As; and b. warming the reactants to the melting point of the second reactant. 